fix race in t/watcher.t
fix race in t/watcher.t

didn't notice this when merging... when on a single core system it's
likely the log thread hasn't dequeued everything, so the test can get
multiple lines. look for the right one.

dormando/memcached,memcached/memcached,memcached/memcached,dormando/memcached,memcached/memcached,dormando/memcached,dormando/memcached,memcached/memcached,memcached/memcached,dormando/memcached